A number of industrially significant processes produce as a waste product dilute solutions of short chain carboxylic acids, particularly formic acid and acetic acid. Typically these solutions are in the range of one to three percent acid by weight. Heretofore it has been common to discard such solutions to the environment, but present day concerns about pollution are increasingly making it necessary to clean such waste water solutions and/or to recover the acids that they contain as economically valuable byproducts of the processes.
Conventional recovery systems, such as distillation, or extractive distillation, tend to be objectionably energy intensive and uneconomical, as well as involving process difficulties such as the formation of azeotropes and difficult-to-break emulsions and the like.
There is thus a need for a method of treating waste water containing short chain carboxylic acids in a manner which will produce a waste water product which needs little or no after treatment before its ultimate discharge or reuse as process water in a plant, and which produces recovered carboxylic acids of such purity and quality as to be saleable or reusable in a process plant, in an economical manner. The present invention is designed to fill that need.